Post by PUshift on Oct 9, 2010 18:21:00 GMT -4
Could somebody be so kind to verify weather the LM DPS on its descent on PDI had used its engine gimbal-functionality to change the attitude (i.e. pitch down from 90 to 70°, later to 30° and further down to zero until the horizontal stop) or were all changes of attitude made by firing the RCS quads?
I hope to know for sure that the ascent went on RCS control only.
But so far I believed in the use of gimbal control while descending.
I experienced this as a very precise way to control the vehicle on my trials to land the LM in ORBITER (Apollo NASSP 6.4.3) which surely doesn´t count in any respect.
But like in reality there is a switch called "ENG GIMB" which can be set either to "enabled" or "on". The gimbal control works on "enabled" only (in the simulation).
I suggest that the "on"-position at least allowed the calibration of "centre-of-gravity", for which the DPS engine was initially run at only 10 per cent thrust for the first 26 seconds. (not really simulated in Orbiter).
Now some well experienced people of a german forum tell me that the PDI ran on RCS control only. Gimbaling only for holding centre-of-gravity.
In W.David Woods "How Apollo flew to the moon", page 244 it is mentioned, that the ability to vector the thrust was not intended to steer the craft because it had been to slow for that. So this correlates with the given assertion.
Ok, PC-Simulations don´t give any garantee to copy reality. But the switch existed really, it can be found directly above the famous "descent command override" on the left side of the LM panel. And it had to be worth for something. Was the "enabled"-position any backup for redundancy in case of RCS failure but was never used?
I remind to have read anywhere (cannot remember, where) apollo astronauts described the behavior of the LM control as very effective, directive, "squared" or how it´s been said. Just fitting to the quick changes of attitude by gimbaling which doesn´t only start but also stop the rotation in a very fast and direct manner.
I would like to know the position the "ENG GIMB" switch and how it was done in reality of the apollo missions.
(for the 3 stages of the SaturnV, with that huge weight and inside the atmosphere I cannot imagine any other control of attitude than gimbaling the main engines. If that should be wrong I will loose my whole confidence in the belief to know anything about how apollo worked.)
Thanks a lot in advance!
I hope to know for sure that the ascent went on RCS control only.
But so far I believed in the use of gimbal control while descending.
I experienced this as a very precise way to control the vehicle on my trials to land the LM in ORBITER (Apollo NASSP 6.4.3) which surely doesn´t count in any respect.
But like in reality there is a switch called "ENG GIMB" which can be set either to "enabled" or "on". The gimbal control works on "enabled" only (in the simulation).
I suggest that the "on"-position at least allowed the calibration of "centre-of-gravity", for which the DPS engine was initially run at only 10 per cent thrust for the first 26 seconds. (not really simulated in Orbiter).
Now some well experienced people of a german forum tell me that the PDI ran on RCS control only. Gimbaling only for holding centre-of-gravity.
In W.David Woods "How Apollo flew to the moon", page 244 it is mentioned, that the ability to vector the thrust was not intended to steer the craft because it had been to slow for that. So this correlates with the given assertion.
Ok, PC-Simulations don´t give any garantee to copy reality. But the switch existed really, it can be found directly above the famous "descent command override" on the left side of the LM panel. And it had to be worth for something. Was the "enabled"-position any backup for redundancy in case of RCS failure but was never used?
I remind to have read anywhere (cannot remember, where) apollo astronauts described the behavior of the LM control as very effective, directive, "squared" or how it´s been said. Just fitting to the quick changes of attitude by gimbaling which doesn´t only start but also stop the rotation in a very fast and direct manner.
I would like to know the position the "ENG GIMB" switch and how it was done in reality of the apollo missions.
(for the 3 stages of the SaturnV, with that huge weight and inside the atmosphere I cannot imagine any other control of attitude than gimbaling the main engines. If that should be wrong I will loose my whole confidence in the belief to know anything about how apollo worked.)
Thanks a lot in advance!